Brush-holder for dynamo-electric machines



J. s. DEAN. BRUSH HOLDER FOR DYNAMO ELECTRIC MACHiNES.

APPHCATION FILED NOV-3.191].

Patented Dec. 28, 1920.

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INVENTOR Jb/m 5 Dean ATTORNEY UNITED STATES, PATENT OFFICE.

JOHN S. DEAN, OF EDGEWOOD PARK, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

BRUSH-HOLDER FOR DYNAMIC-ELECTRIC MACHINES.

Application filed November 3, 1917.

To all whom it may concern:

Be it known that 1, JOHN DEAN, a citizen of the United States, and a resident of Edgewood Park, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Brush-Holders for Dynamo-Electric Machines, of which the following is a specification.

My invention relates to brush-holders for dynamo-electric machines, and it has for its object to provide an insulator for the brushholder supporting pin that will not crack, when subjected to strains or sudden jolts, and that will prevent any current from pass in over the surface along creepage paths.

eretofore, it has been customary in brush-holder construction, to employ corrugated porcelain insulators, and, while they have ordinarily given good service, there have been frequent instances where the insulators were cracked or were loose upon the supporting pins, and a creepage path was established that was equal in length to the thickness of the insulator. Either of these occurrences provides a short creepage path for the current and also a support for any particles of foreign matter that may become lodged in the crack in the insulator, or between the insulator and the supporting pin, and which may be a part of the creepage path.

According to my invention, I provide an insulating sleeve composed of fibrous material that is more resilient than porcelain, and, therefore, not so liable to become broken. Also, the creepage path is purposely made considerably longer and of such irregularity that it is difficult for a current to traverse it. Another advantage is that several insulators constructed in ac cordance with my invention may be placed upon a standard supporting pin for use in high-voltage apparatus. When more than one insulator, of the type now in use, is desired on a single support, a special pin, longer than the standard, must be used.

Referring to the accompanying drawings, Figure 1 is a partially sectional and par tially elevational view of a current-collecting device constructed in accordance with my invention. Fig. 2 is a cross-sectional Specification sf Letters Patent.

Patented Dec. 28, 1920.

Serial No. 200,002.

view of a modification of the apparatus shown in Fig. 1, and Figs. 3 and at are cross-sectional views of apparatus designed for high-voltage service.

The brush-holder usually comprises main body member 1 that is provided, at one end, with a brush 2 mounted in a brush box 3 and is adapted to engage a coacting rotatable surface 4 of a dynamo-electric machine (not shown). At the other end, the Ina1n body member is mounted on the machine frame 5 by means of a supporting pin 6.

The supporting pin 6, is insulated from the frame 5 by means of a fibrous insulating sleeve 7 and an insulating washer 8. The portion 9 of the sleeve 7 that is adjacent to the machine frame 5 is cylindrical and fits snugly against the supporting pin 6. The portion 10 of the sleeve 7 is adjacent to a brush-holder body 1 and is flared to a frusto-conical shape, surrounding, but not 1n engagement with, the pin 6.

In that modification shown in Fig. 2, the pin 6 is so cut away that it is not in engagement with the insulating sleeve 10 which is cylindrical. In Fig. 3, the flared sleeve 7 is mounted upon an entirely cylindrical sleeve 11, and, in Fig. 4, a short sleeve 12, that is doubled back upon itself, is placed around the cylindrical sleeve 11. Both insulators, as shown in Figs. 3 and 4, are used on exceptionally high-voltage apparatus, as the length of the creepage path is increased about 50%.

From the foregoing description, it will be readily apparent to those skilled in the art that insulators of this general character provide especially long creepage paths of such a shape that foreign particles, which frequently provide creepage paths, do not readily adhere thereto. On account of the sleeve being made of fibrous material, it does not crack when subjected to strains or sudden jolts.

While I have shown my invention in a plurality of forms, it will be obvious to those skilled in the art that it is not so limited but is susceptible of various minor changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or are specifically set forth in the appended claims.

1 claim as my invention:

1. in a dynamo-electric machine, the combination with a brush-holder comprising a brush-holder body attached to said dynamoelectric machine frame by means of a supporting pin, of an insulating sleeve surrounding said pin, a portion of which is cylindrical in shape and fits snugly against said pin and another portion of which is frusto-conical in shape, surrounding, but not in engagement with, said pin.

2. In a dynamo-electric machine, the combination with a brush-holder comprising a brush-holder body attached to said dynamo electric machine frame by means of a supporting pin, of a sleeve of fibrous insulating material surrounding said pin, the portion adjacent said frame being cylindrical in shape and fitting snugly against said pin and the portion adjacent to said brushholder body being frusto-conical in shape surrounding, but not in engagement with, said pin. v Y

In testimony whereof I have hereunto subscribed my name this l9th day of Oct.

JOHN S. DEAN. 

